Let-7g 介导细胞自噬在骨肉瘤恶性表型中的作用与机制研究

The pulmonary metastasis is the main reason of death for patients with osteosarcoma. Therefore, to make clear the molecular mechanism of metastasis for improving the curative effect has become one of the hotspot problems needing solve. It is found that autophagy plays an important role in the malignant phenotype of osteosarcoma. However, the molecular mechanism of it is not clear. Now it is proved that autophagy of tumor cell mediated by PI3K / Akt / NF-κB signaling pathway promotes malignant phenotype of tumor. In our previously studies, we found that RNAi silencing aurora-B expression in osteosarcoma cells could reduce the activity of PI3K / Akt / NF-κB signaling pathway and inhibit the malignant phenotype of osteosarcoma. And let-7g negative regulated the expression of aurora-B and inhibited osteosarcoma cell migration and invasion in vitro. Based on these results, we will conduct study using human osteosarcoma tissue, cell and mice to confirm whether autophagy promotes invasion and metastasis of osteosarcoma mediated by let-7g with molecular genetics and biology methods. In advance, we will explore the molecular mechanisms of let-7g mediating autophagy of osteosarcoma via regulating the activity of aurora-B / PI3K / Akt / NF-κB signaling pathway in vitro and vivo. If this study was completed successfully, the new therapeutic strategies would be provided for preventing and treating metastasis of osteosarcoma.

肺部转移是骨肉瘤患者死亡最主要的原因，因此阐明骨肉瘤侵袭转移的分子机制是目前防治研究的热点之一。研究发现细胞自噬在骨肉瘤恶性表型中起重要作用，但其分子机制尚不清楚。目前已证实PI3K/Akt/NF-κB通路介导肿瘤细胞自噬，促进肿瘤恶性表型。我们前期研究发现RNAi沉默Aurora-B在骨肉瘤细胞中的表达可下调PI3K/Akt/NF-κB信号通路活性而抑制骨肉瘤细胞恶性表型；let-7g 负向调控Aurora-B 抑制骨肉瘤细胞体外迁徙侵袭。因此，本研究拟以人骨肉瘤组织、细胞和裸鼠为研究对象，采用分子遗传学和肿瘤分子生物学方法，试图证实let-7g通过介导细胞自噬促进骨肉瘤侵袭转移；另外，从改变let-7g 表达对Aurora-B/PI3K/Akt/NF-κB信号通路活性的影响探讨其介导骨肉瘤细胞自噬的可能分子机制。本研究的顺利完成将为骨肉瘤侵袭转移的防治提供新的干预环节和治疗策略。

骨肉瘤是儿童和青少年最常见的原发性恶性骨肿瘤，肺部转移是骨肉瘤患者死亡最主要的原因，因此阐明骨肉瘤侵袭转移的分子机制是骨肉瘤肺转移防治研究的热点。文献证实细胞自噬在骨肉瘤恶性表型中起重要作用，但其分子机制尚不清楚。我们前期研究发现，RNAi沉默Aurora-B在骨肉瘤细胞中的表达可下调PI3K/Akt/NF-κB信号通路活性而抑制骨肉瘤细胞恶性表型；let-7g可负向调控Aurora-B 抑制骨肉瘤细胞体外迁徙侵袭。本项目中，我们以人骨肉瘤组织、细胞和裸鼠为研究对象，采用分子遗传学和肿瘤分子生物学方法，检测骨肉瘤组织和细胞中let-7g的表达水平，并分析let-7g 与骨肉瘤细胞自噬的关系；通过细胞体外实验和裸鼠体内实验，论证 let-7g 低表达激活 Auraro-B/ PI3K/ AKT/ NF-κB 信号通路介导细胞自噬促进骨肉瘤恶性表型。. 结果显示，let-7g在骨肉瘤组织和细胞中呈低表达； let-7g 高表达抑制细胞自噬，进而抑制骨肉瘤细胞恶性增殖及集落形成能力。体外实验发现，let-7g 低表达激活 Auraro-B/ PI3K/ AKT/ NF-κB 信号通路，并促进细胞自噬。进一步裸鼠体内实验证实，let-7g 低表达激活 Auraro-B/ PI3K/ AKT/ NF-κB 信号通路促进细胞自噬，导致裸鼠生长状态恶化和肿瘤体积增加。. 通过本项目的实施，我们证实了let-7g 低表达激活Auraro-B/PI3K/AKT/NF-κB 信号通路介导细胞自噬，促进了骨肉瘤细胞恶性增殖。本项目的顺利完成将为骨肉瘤侵袭转移的防治提供新的干预环节和治疗策略。